Waste materials present ever-increasing disposal problems.
In the past, refuse and toxic waste were often burned. However, due to increased governmental and regulatory standards, the potential public health impacts of carcinogenic air emissions, such as dioxins and furans, and the risks of spreading toxic plumes, the burning of wastes has generally been abandoned.
Efforts have been made to replace burning of waste with pyrolysis processes that would provide for safe combustion with minimal emissions and allow recovery of heat from combustion.
U.S. Pat. No. 6,758,150, the full disclosure of which is incorporated herein by reference, describes a system for pyrolysis of waste material. The system includes a pyrolysis unit, a thermal oxidizer unit, and a stack unit. The pyrolysis unit includes a first retort disposed within a combustion chamber and a second retort disposed outside the combustion chamber. The combustion chamber supplies heat, which pyrolyzes the waste material as it is conveyed through the first retort. The thermal oxidizer oxidizes pyrolysis gases from the first retort and the stack unit provides a draft to move the pyrolysis gases through the thermal oxidizer. Flue gases from the combustion chamber are vented to atmosphere.